SPECIAL DEPARTMENT COLLOQUIUM | Climate Change and Energy Solutions<

Speaker: Frank H. Shu (University Professor Emeritus, University of California)

This is a joint event sponsored by Nuclear Engineering and Radiological Sciences, Chemical Engineering, & the Physics Department.

The greatest challenge facing civilization in the twenty-first century is climate change
induced by the net emission of carbon dioxide by human activity. We review the science
behind this subject from an astronomer’s perspective, using well-understood principles
underlying the balance of heating by the light from the Sun and the cooling of the Earth’s
infrared radiation back to space. We investigate the evidence locked in Antarctic ice
cores of past cycles of runaway warming and cooling (interglacial periods and ice ages)
and their relationship to astronomical phenomena (the Milankovich cycle), and we point
out why current events are different. We also discuss the alarming possibility that the
Earth has already passed the tipping point for the melting of the polar ice. We then give
order of magnitude arguments for the maximum amount of power that we can derive
from alternative sources of energy. Compared to projected needs by mid-century, there
are only five realistic energy choices to reduce or eliminate net carbon-dioxide emissions:
(1) fossil fuel with carbon capture and sequestration, (2) biofuels, (3) solar photovoltaics/
solar thermal, (4) wind, and (5) nuclear. We point out the drawbacks of the first four. We
then explain the basics of nuclear fission, concluding that reprocessing and breeding are
necessary to remove public concerns about waste management, safety, and sustainability
of the nuclear option. In particular, we point out why the long overlooked technologies
of molten salt reactors coupled to the thorium fuel cycle is superior in terms of cost,
passive safety, and weapons non-proliferation to the current usage of nuclear power. We
discuss an approach using novel materials to build two-fluid molten salt reactors on a
rapid enough schedule to make America and the world free of plutonium and net CO2
emission by mid-century. Of particular interest may be the possibility of leveraging the
capacity of such facilities by coupling nuclear power to the production of artificial coal.
The latter holds the promise of making existing coal-fired power plants not only carbon
neutral, but even carbon negative. In this manner, it may be possible to reverse human-
induced climate change and pass on to future generations a mode of living compatible
with satisfying the economic aspirations of billions of people now living in poverty and a
greener, more benign, and more bountiful planet.